A Club for YL Ham Radio Operators

Zero Beat

What the heck is that?

In the MINOW preamble is the phrase “please zero beat this frequency”. I was asked what exactly that means. Well, I had the same question several years ago and asked my OM. However, I don’t remember his explanation, so I went to the internet.

Here’s the definition I found “Definition of zero beat. : a condition in which two radio frequencies are adjusted to equality by first producing beats between them and then reducing the beat frequency to zero — compare heterodyne.”

OK, that really doesn’t help too much. So I went to Google and found the following “conversation”

Scott Dordick:. My rig is a Kenwood TS130S. How do I zero beat properly on SSB? I have had my general license for about 5 days now. Yesterday I particapated in my first HF SSB (40 meter) net. I was told I was below frequiency(sic) and to zero beat. I was able to get on frequiency(sic) by dialing up my frequiency(sic) until net control said I was on. Then dialing my receive back with the RIT. My rig is a kenwood(sic) TS130S. How do I zero beat properly on SSB?

Pete Allen: HI: First: "zero beat" means beating a station you are listening to's carrier against your transmitter's local oscillator. As you get closer and closer the tone you hear will go from a whistle to a growl to a thump-thump-thump. When the thump stops you are "zero beat," exactly on the other station's transmit frequency.

But SSB has no carrier to beat against. So you literally cannot zero beat an SSB signal. The best you can do is what you did do. Tune your reciever(sic) until the other station sounds as natural as possible and call them.

If they say you are "off frequency" for some reason, perhaps your voice is higher or lower in pitch than they expect it to be, do exactly what you did. Tune them in as best you can and adjust your RIT until they sound good to you.

However, if you keep on having this problem in general hamming - your BFO or your LO may have gotten a little off frequency off over the years and your rig might well benefit from a professional realignment.

–73 Pete Allen AC5E

I think Pete did a wonderful job of explaining what was going on.

By the way for those who don’t know what RIT is… RIT is a knob on your radio. The acronym stands for “Receiver Incremental Tuning”. I use it when someone is slightly off frequency (the voice sounds kind of weird like the speaker is talking into a rain barrel). I adjust the RIT a few cycles until the voice sounds “normal”. When the speaker finishes the transmission, I turn the RIT off and the other voices on the QSO sound OK. When the speaker comes back on, I turn the RIT back on and the speaker sounds normal again. This usually occurs because a radio is not exactly on the frequency that it should be or because propagation has altered the signal slightly.

~ Margaret Hardwick, AE7MB – September 2017